Corals are marine organisms containing calcium carbonate as a principal component with a number of trace metals present in seawater, and coral powder prepared by calcination and grinding of weathered corals is used in, for example, healthy foods to be ingested as a source of minerals.
For example, Patent Document 1 describes a deodorant obtained by crushing a calcified coral into a fine powder, establishing a complete oxygen-free condition in a nitrogen flow, increasing temperature while gradually allowing hydrogen to flow thereinto as a gas stream to adjust the ratio of nitrogen and hydrogen to 8:2 to 6:4, and increasing temperature to 600 to 800° C. to perform reductive calcination, and also describes an anti-oxidant food obtained by applying the deodorant to a healthy food.
Patent Documents 2 and 3 disclose a coral calcium powder to which negative hydrogen ions are added or adsorbed and a method for producing the same. A healthy food having a coral powder to which negative hydrogen ions are adsorbed is published on a website (www.kenko-suiso.com) on the Internet and the like.
Patent Documents 4 and 5 disclose a coral powder as a substance that reacts with water to release hydrogen.
These corals and seashells obtained by calcinating marine organisms are utilized as fertilizers because they are more easily dissolved in water than common calcium materials and smoothly absorbed into plants, have stably sustained effects for a long period, and grow tissue skeleton ducts of crop plants well, so that aqueous solutions containing nutrients are efficiently circulated in plants, and the production efficiency of substances produced by photosynthesis is improved.    Patent Document 1: Japanese Patent Laid-Open No. 2007-236851    Patent Document 2: Japanese Patent Laid-Open No. 2005-245265    Patent Document 3: Japanese Patent Laid-Open No. 2007-217351    Patent Document 4: Japanese Patent Laid-Open No. 2006-176483    Patent Document 5: Japanese Patent Laid-Open No. 2005-007380